As a form of an electric parking brake device, a structure disclosed in Patent Literature 1 has been known. An electric parking brake shown in FIG. 1 of Patent Literature 1 is structured as follows. A propulsion member 35 moves in a direction where brake pads 24, 25 come into contact with a disc rotor 4 by driving electric motors 32 in a positive rotation. The propulsion member 35 moves a piston 29, so that the piston 29 presses each of the brake pads 24, 25 against the disc rotor 4 as lock operation.
As a form of a disc brake device for a vehicle, a structure disclosed in Patent Literature 2 has been known. In a disc brake device for a vehicle shown in FIG. 1 of Patent Literature 2, a pad 12 (inner pad) and a shim 28 are engaged with each other through an engaging long hole 32 and a projection 34. Therefore, each of the pad 12 and the shim 28 is restrained from relatively rotating about a central axis of the piston.